Very useful feedback

I got very valuable feedback from mdk777, who clearly know’s internals of PSU-s very well. This is very big setback and makes my PSU really unuseable. Currenly I’m thinking to go to 2 PSU solution.

Thermaltake 12v rails

Sent at: 17 Feb 2009, 18:32
From: mdk777
To: jaak ennuste 

Hey Jaak,      

Further on the Thermaltake Power supply:

If you download their manual from the web site (the model that you ordered from your site) you will see that the four rails are split.
The PCIE are ALL on V3 and V4.
While THermaltake claims huge overall wattage, V3 and V4 are only rated for 40 amps each.

Hence your 1500 watt rated power supply will only be supplying 80 amps to your four cards!!!

EVGA recommends 46 amps on the 12 v rail PER CARD. We know this is high, but just throwing it out to show that the Thermaltake is really only good for two cards and not 4.

Thermaltake is not the highest rated or the highest quality power supply maker.
As I mentioned posting on your web site, I would hate to see you burn up more equipment.

In comparison, one 850 watt corsair power supply has a single 12v rail rated at 70 amps. (129$ at the egg, I know not your favorite supplier, but I think corsair has a presence in the EU)

Two of these would get you 140 amps available on the 12v rail. instead of the 80 amps you will be getting with the Thermaltake.

Best of luck however you go.

——————————————-

Hmm, interesting. 40 Amperes per 12 volts DC means 480 Watts. NVIDIA GTX 295 tech specs say, that it tdraws 289 Watts under full load. It’s 24 Amperes, far from 46 Amps, required by EVGA? I don’t really understan as huge required reserve.

In my direct measurements system w 3 x GTX 295 pulled 900 Watts from the wall. Say, 15% is PSU loss, system board and each card draws 200 Watts, no more.

 

 

3 Comments

  1. Jaak,

    Thanks for the kind words, but I am no expert.
    The 46 AMPS that EVGA recommends is for the entire system.
    The problem with power supply ratings is that they are likewise, for the entire system.
    However, 4 X GTX 295 cards require the amps to be available on the 12 v rails going to the card! I don’t mean to say that Thermaltake is a poor quality supplier, I just wanted to point out that total watt rating does not always translate into available power to the specific, high load usage that we require. Let’s face it, there just are not that many people trying to run 4 X GTX 295 cards, 24/7/365 off one motherboard and one power supply!! Thermaltake might be the exception, but if it were my money, I would be running well under the max load rating (aiming for 50%-80%) to insure longer life and reduced chance of damage to my equipment.
    Good luck again.

  2. Excellent blog!

  3. Thanks Kristleifur. Are You from Iceland?

    Jaak


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